The present invention relates to an apparatus for retrieving a cartridge, such as an optical disk cartridge, from a storage array so that the cartridge may be moved to an alternate location.
Optical disks are an increasingly popular medium for digitally storing information. Optical disks are typically enclosed in box shaped disk cartridges having two notches formed near one end of the cartridge, with one notch located on each long side.
In some large-scale optical disk storage and retrieval systems, disks are stored in an array of storage slots, with each slot positioned vertically of the other slots to form a column. The storage systems often have several such columns arranged laterally of each other to form a two dimensional array of slots. The systems include disk retrieval mechanisms which use gripping means to retrieve a selected cartridge from its storage slot, transfer the cartridge to a disk reader, and to subsequently return the cartridge to its slot when instructed to do so. The gripping means normally grips the cartridge by engaging with the notches located on the side of the cartridge.
One necessary feature in the design of cartridge retrieval and return systems is a gripping means that is convertible between a retrieval mode, in which the gripping means is capable of engaging and carrying a disk cartridge, and a return mode in which the gripping means releases the disk cartridge so that it may be returned to its storage location. One presently available cartridge retrieval mechanism, described in U.S. Pat. No. 5,014,255, utilizes a pair of gripping arms proportioned for engaging the notches located on the sides of a disk cartridge. The gripping arms are pivotally mounted to a carriage which travels towards the disk cartridge. A spring biases the gripping arms inwardly such that when forward advancement of the carriage causes them to abut the end of a disk cartridge, the edges of the cartridge urge them laterally outward until they slip inwardly into engagement with the notches on the cartridge. The gripper arms and the carriage are disposed between a pair of rectangular plates which are connected at one end and which are proportioned to fit a retrieved cartridge between them.
A disadvantage with the currently available disk cartridge retrieval systems such as the one described above is that proper positioning of the gripper arms is conditioned upon proper positioning of guide members that move independently of the gripper arms. The change in position of the guide members that is needed to properly position the gripper arms is triggered by movement of the carriage and is only on the order of a few millimeters. Accurate positioning of each gripper arm is contingent upon successful travel of a small peg attached to that gripper arm through one of a series of narrow channels. Each peg is guided into the appropriate channel by proper positioning of one of the guide members. The device is thus highly tolerance-dependent, has an increased likelihood of malfunction caused by improper alignment of moving parts, and is expensive to construct in such a way as to achieve adequate precision.
Yet another disadvantage with currently available systems is that the components used for biasing the gripper arms are configured such that excessive force is exerted on the biasing spring when the gripper arm is pivoted laterally of the carriage during ejection of a cartridge. The force on the biasing spring increases well above the normal spring rate and thereby exposes the spring and other components to substantial forces that can precipitate premature wear.
It is an object of the present invention to provide an improved cartridge engagement system which is less tolerance-dependent than currently available systems so as to allow for relatively inexpensive top-down assembly and decreased likelihood of malfunction. It is another object of the present invention to provide an improved cartridge engagement system having a gripper arm biasing mechanism that will minimize stresses on components and that will therefore increase the longevity of component parts.
The present invention is intended for use with a carriage slidable along a longitudinal path formed in a base. A pair of gripping arms are pivotally mounted on the carriage, with their distal ends extending distally from the carriage. The gripping arms are configured such that when they are advanced against the cartridge positioned at the distal end of the longitudinal path, they will deflect laterally around the proximal corners of the cartridge until they engage the notches formed in the cartridge.
Biasing springs are connected to the gripping arms so as to bias the gripping arms in one of two different biasing conditions. In the first biasing condition, the gripping arms are biased towards each other so that when advanced against a cartridge they will deflect into engagement with the notches as described above. In the second biasing condition, the gripping arms are biased outwardly and are thus unable to engage or remain engaged with a cartridge.
A pair of setting components, each of which is connected to one end of a biasing spring, are mounted to the carriage. During longitudinal travel of the carriage, the setting components collide with camming members extending into the longitudinal path of the carriage. The camming members move the setting components laterally outward into a first position or laterally inward into a second position, depending upon the direction of travel of the carriage. When the carriage travels in the proximal direction, the camming members close a gap between the setting components and thereby cause the biasing springs to pivot into a second spring orientation which produces the second biasing condition. During travel in the distal direction, the camming members separate the setting components, thereby causing the biasing members to pivot into a first spring orientation which will produce the first biasing condition.
In a preferred embodiment, additional camming components are mounted to the base which catch the gripper arms and pivot them to a laterally extending position during ejection of the cartridge and which again catch the gripper arms to pivot them back into the distally extending position during the withdrawal of the carriage which follows ejection. The biasing springs are configured such that pivoting the gripper arms into the laterally extending position does not oppose the direction of bias but instead alters it so as to minimize stresses on the springs and surrounding parts. An additional spring is connected between each gripper arm and its corresponding biasing spring to prevent abrupt rotation of the gripper arm between the distally extending and laterally extending positions.